Also it often becomes possible to see the black area below the skybox, which is bad for promotional screenshots.
(There are also other methods to draw the skybox. For example it can has the size 1x1x1, but be rendered independent of the world position of the camera with a different openGL projection, so that the skybox appears infinitely far away.
If good textures are chosen, the box shape of the skyset will also become unnoticeable.)
